HSPA8 and Parkinson disease: For example, many studies have now identified mutations or truncations in DNAJ, the gene that encodes for the Hsc70 co-chaperone, auxilin, in patients with juvenile Parkinsonism or early-onset PD (Edvardson et al., 2012; Köroğlu et al., 2013; Elsayed et al., 2016; Olgiati et al., 2016).